This application claims the priority of Korean Patent Application No. 10-2002-0067974 filed on Nov. 4, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of Invention
The present invention relates to a system and method for detecting a face, and more particularly, to a system and method for detecting a face that is capable of quickly and correctly deciding, using an algorithm for determining whether a face is occluded, whether an input facial image is occluded.
2. Description of the Related Art
As the information society advances, automatic teller machines have rapidly come into wide use. Financial crimes in which money is illegally withdrawn using credit cards or passwords of other persons have also increased. To deter these financial crimes, a CCTV is installed in automatic teller machines to identify criminals. However, criminals often commit these crimes while wearing sunglasses or caps so as not to be photographed by the CCTV, and thus, it makes it difficult to identify the faces of the criminals.
Korean Patent No. 0306355 (entitled “User identification system and automatic teller machine using the same”) discloses a user identification system for identifying the face of a user, by acquiring a facial image of the user, obtaining a facial region through filtering of only a skin color region, extracting an eye position from the obtained region, setting a range of a mouth and nose on the basis of the eye position, and checking whether confirmable characteristic points exist. However, the eye position is extracted and the mouth and nose positions are then extracted on the basis of the extracted eye positions. Thus, if eye positions are not extracted, it is difficult to extract the mouth and nose positions. Further, image data of the user is not searched but the presence of facial components (e.g., eyes, nose, mouth, and the like) is merely checked to identify the user. Thus, the face detection of a user cannot be correctly performed.
In addition, Korean Patent No. 0293897 (entitled “Method for recognizing face of user of bank transaction system”) discloses a method for recognizing the face of a user, which comprises the steps of determining facial candidate entities matching with an input user image using chain tracking, extracting contour points and comparing brightness values of the contour points to search graphics corresponding to eyes and mouth of the user, calculating a recognition index for the face, extracting only a single facial candidate entity, and comparing the recognition index for the face of the extracted facial candidate entity with a reference recognition index for the face. However, the presence of the eyes and mouth is determined according to whether the contour points of the eyes or mouth have been extracted. Thus, there is a possibility of misrecognizing sunglasses as eyes in a case where the sunglasses a user wears are similar to the eyes of the user in view of their shape and size.
Furthermore, since conventional face detection technology uses color images, it is difficult to detect feature points for the nose and mouth of the user due to illumination. Consequently, the feature points of the nose and mouth of the user may not be detected. Therefore, there is also a problem in that the legal user may be recognized as an illegal user.